The invention relates to internal combustion engines of the type in which fuel is injected into the combustion chambers by electronically controlled injection valves associated with the respective chambers. More specifically, it relates to a method and apparatus in which combustion chamber identification in an internal combustion engine of this general character is accomplished in a simple and highly efficient and effective manner.
In fuel-injection combustion engines, it may become difficult for various reasons to obtain without any additional sensors, e.g., on the camshaft of the engine, signals for associating the individual combustion chambers and, respectively, the torque shares generated by them, on the one hand, and the injection valves therefor on the other hand. In the case of injection valves actuated at different times, these difficulties are due to the fact that a working cycle of four-stroke engines extends over two rotations of the crankshaft. In a 4-cylinder 4-stroke Otto engine, for example, with the ignition sequence 1-3-4-2, two cylinders, namely 1 and 4, or 2 and 3, would always attain upper dead center simultaneously, but the inlet valve of only one of the two cylinders in TDC-state is opened, i.e. the cylinder is sucking in. This cylinder must be known in order to synchronize the electronic fuel injection to deliver fuel into the intake port of this cylinder only. In the case of other known fuel-injection engines, there occurs simultaneously a fuel advance feed into the intake ports of all combustion chambers, so that here, again, the state of the art requires additional camshaft sensors for obtaining such association signals.
The necessity of combustion chamber identification also arises if undesirable hunting, i.e. an unevenness in engine speed, resulting from differences in engine torques created in the individual cylinders, occurs. In order to alter an engine parameter only for the cylinder causing said hunting in a manner to eliminate the unevenness it is necessary to know this cylinder.
It is an object of the invention to provide a method and apparatus for combustion chamber identification in an internal combustion engine without the use of additional sensors, e.g, on the camshaft of the engine.